The present invention is generally directed to toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner resins, especially polyesters, and toner compositions thereof. In embodiments, the present invention is directed to the economical in situ, chemical or direct preparation of toners and toner resins without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with an average volume diameter of from about 1 to about 25, and preferably from 1 to about 10 microns and narrow GSD of, for example, from about 1.16 to about 1.26 or about 1.18 to about 1.28 as measured on the Coulter Counter can be obtained, and wherein flushed pigments are selected thus enabling toners with low melting characteristics, and which toners contain certain polyester resins. With flushed pigments, there is enabled a superior uniform dispersion of the pigment within the low melt resin, permitting optimum pigment/polymer loading and improved toner quality. Embodiments of the present invention relate to a process for the preparation of dry toner compositions comprised of resin and pigment, and which process comprises flushing a pigment into a sulfonated polyester resin, referred to as a flushed pigmented system, followed by dissipating the flushed pigmented system in water to obtain pigmented particles. The degree of sulfonation during the preparation of the sulfonated polyester resin can be a primary factor in determining the size of the toner particles obtained during the dissipating step. The process of the present invention relates to the preparation of toner particles by (i) dissipation of a flushed pigmented sulfonated polyester in water, preferably heated warm or hot water (&gt;60.degree. C.) to obtain submicron pigmented sulfonated polyester particles which are in the range of about 5 to about 200, about 5 to about 150, or about 50 to 200 nanometers in size diameter; followed by heating the resulting mixture below about the glass transition temperature of the sulfonated polyester; and adding a metal salt halide such as magnesium halide and preferably an aqueous magnesium chloride solution wherein the concentration of the solution is in the range of from about 0.5 to about 5 weight percent; or optionally adding the magnesium chloride solution during the heating from room temperature to a temperature below the resin Tg (chemical toner); or (ii) preparing pigmented toner size particles directly prepared from the flushed pigment system upon dissipating in water where the particles obtained are in the size range of from about 3 to about 7 microns in volume average diameter. The resulting toners from either (i) or (ii) can be selected for known electrophotographic imaging methods, printing processes, including color processes, and lithography (direct toner). More specifically, with the processes of the present invention, the use of surfactants can be avoided, for example nonionic surfactant is not needed to disperse the pigment selected, cationic surfactant is not needed to perform the aggregation, and the anionic surfactant selected to stabilize the aggregated particles when heated to 20.degree. C. to 40.degree. C. above the resin Tg during the coalescence, reference for example U.S. Pat. No. 5,403,693, the disclosure of which is totally incorporated herein by reference, followed by washing to remove surfactants is eliminated (chemical toner). The process of the present invention enables the utilization of polymers obtained by polycondensation reactions, such as polyesters, and more specifically, the sulfonated polyesters as illustrated in U.S. Pat. No. 5,348,832, and U.S. Ser. No. 595,143, now U.S. Pat. No. 5,604,076, the disclosures of which are totally incorporated herein by reference, and which polyesters can be selected for low melting toners. With the processes of the present invention, there are generated flushed pigmented polyesters wherein the polyester has a varying degree of sulfonation which upon dissipation in warm water results in particles of (i) about 3 to about 7 microns in size (direct toner), (ii) submicron pigmented particles of from about 50 to about 200 nanometers in size which particles are then aggregated to toner size, about 3 to about 7 microns, wherein the charging and fusing of the toners containing these polyesters is not substantially adversely affected by residual surfactants (chemical toner).
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic or basic polar groups and a coloring agent. The polymers selected for the toners of the '127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this '127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. Also, see column 9, lines 50 to 55, wherein a polar monomer, such as acrylic acid, in the emulsion resin is necessary, and toner preparation is not obtained without the use, for example, of acrylic acid polar group, see Comparative Example I. In U.S. Pat. No. 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component, and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70 are obtained. Other prior art may include U.S. Pat. No. 3,674,736; 4,137,188 and 5,066,560.
Emulsion/aggregation processes for the preparation of toners are illustrated in a number of patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. No. 5,290,654, U.S. Pat. No. 5,278,020, U.S. Pat. No. 5,308,734, U.S. Pat. No. 5,346,797, U.S. Pat. No. 5,370,963, U.S. Pat. No. 5,344,738, U.S. Pat. No. 5,403,693, U.S. Pat. No. 5,418,108, U.S. Pat. No. 5,364,729, and U.S. Pat. No. 5,346,797.